Comparison of pH-state and Alpha-stat Cardiopulmonary Bypass on Cerebral Oxygenation and Blood Flow in Relation to Hypothermic Circulatory Arrest in Piglets

Kurth, Dean; O’Rourke, Maureen M.; OʼHara, Irene B.

doi:10.1097/00000542-199807000-00018

Cited by 74 publications

(33 citation statements)

References 38 publications

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“…In addition, during the first minutes of rewarming, the cerebral microvascular diameter was significantly larger when the pH-stat management was used. Kurth et al (22) showed that in newborn piglets, pH-stat improved brain cooling efficiency during CPB and that all regions cooled more rapidly with using this management.…”

Section: Discussionmentioning

confidence: 99%

Effect of deep hypothermic circulatory arrest followed by low-flow cardiopulmonary bypass on brain metabolism in newborn piglets: Comparison of pH-stat and α-stat management

Pirzadeh

Schears

Pastuszko

et al. 2011

Pediatric Critical Care Medicine

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Objective-To compare the effects of pH-stat and alpha-stat management prior to deep hypothermic circulatory arrest (DHCA) followed by a period of low flow (two rates) cardiopulmonary bypass (CPB) on cortical oxygenation and selected regulatory proteins: Bax, Bcl-2, Caspase-3 and phospho-Akt.Design-Piglets were placed on CPB, cooled with pH-stat or alpha-stat management to 18°C over 30 min, subjected to 30 min DHCA and 1h low flow at 20 (LF-20) or 50 ml/kg/min (LF-50), rewarmed to 37°C, separated from CPB, and recovered for 6 h.Subjects-Newborn piglets, 2-5 days old, randomly assigned to experimental groups.Measurements and main results-Cortical oxygen was measured by oxygen-dependent quenching of phosphorescence; proteins were measured by western blots. The means from 6 experiments ± standard error (SEM) are presented as % of alpha-stat. Significance was by t-test. For LF-20, cortical oxygenation was similar for alpha-stat and pH-stat, whereas for LF-50 it was significantly better using pH-stat. For LF-20, the measured proteins were not different except for Bax in the cortex (214±24%, p=0.006) and hippocampus (118% ± 6%, p=0.024) and Caspase 3 in striatum (126% ± 7%, p=0.019). For LF-50, in pH-stat group: In cortex, Bax and Caspase-3 were lower (72±8%, p=0.001 and 72±10%, p=0.004, respectively) and pAkt was higher (138±12%, p=0.049). In hippocampus, Bcl-2 and Bax were not different but pAkt was higher 212±37% (p=0.005) and Caspase 3 lower (84 ± 4%, p=0.018). In striatum, Bax and pAkt did not differ but Bcl-2 increased (146±11%, p=0.001) and Caspase-3 decreased (81±11%, p=0.042).Conclusions-In this DHCA-LF model, when flow was 20ml/kg/min there was little difference between alpha-stat and pH-stat management. However for LF-50, pH-stat management resulted in better cortical oxygenation during recovery and Bax, Bcl-2, pAkt and Caspase-3 changes consistent with lesser activation of pro-apoptotic signaling with pH-stat than with alpha-stat.

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Section: Discussionmentioning

confidence: 99%

Effect of deep hypothermic circulatory arrest followed by low-flow cardiopulmonary bypass on brain metabolism in newborn piglets: Comparison of pH-stat and α-stat management

Pirzadeh

Schears

Pastuszko

et al. 2011

Pediatric Critical Care Medicine

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“…In contrast, several studies in pig and piglet models of deep hypothermic arrest found improved cerebral physiologic recovery with pH-stat management. [16][17][18][19][20] It is not clear if the outcome of these studies performed in hypothermic pigs in circulatory arrest can be translated to the clinical condition of mild hypothermia in asphyxiated term neonates. Li et al 26 suggested that in mild hypothermia, brain tissue oxygen saturation in ␣-stat management was greater than that in pH-stat management.…”

Section: Studies Comparing the ␣-Stat And Ph-stat Methodsmentioning

confidence: 99%

“…E-mail: f.groenendaal@umcutrecht.nl PEDIATRICS (ISSN Numbers: Print, 0031-4005; Online, 1098-4275). Copyright © 2009 by the American Academy of Pediatrics latory arrest in pigs have shown that pH-stat management could confer neurologic protection against ischemia [16][17][18][19][20]. …”

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confidence: 99%

Blood Gas Values During Hypothermia in Asphyxiated Term Neonates

2009

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The authors have indicated they have no financial relationships relevant to this article to disclose.H YPOTHERMIA HAS BECOME an important novel neuroprotective strategy for asphyxiated term neonates. 1 Most of these neonates will receive mechanical ventilation. Hypothermia affects blood gas parameters such as pH and PCO 2 . At lower temperatures pH increases and PCO 2 decreases. This is relevant, because PaCO 2 is known to affect vascular tone and, hence, cerebral perfusion. 2 In addition, cerebral blood flow decreases during hypothermia, which increases the risk of insufficient blood flow during hypocapnia. 3 Most blood gas instruments, whether a central laboratory or point-of-care device, contain a temperaturecontrolled sample chamber specified to be 37°C. It is at that temperature that all measurements of pH and partial pressure of gases are performed. In the ␣-stat strategy, uncorrected values are used to keep the pH and PCO 2 close to the 37°C reference value. 4 However, most instruments can calculate and present temperature-corrected pH and PCO 2 values. In the so-called pH-stat method, the measured pH is corrected to the actual body temperature of the patient. Ventilator settings can be adjusted to keep the actual pH as close to 7.4 as possible. 4 At present, it is unclear whether the ␣-stat or pH-stat theory should be used in the neuroprotective strategy for asphyxiated term neonates.In the 2 large randomized, controlled trials on therapeutic hypothermia in term neonates with perinatal asphyxia, attending physicians were advised to correct blood gases and pH for rectal temperature. 5,6 Here we will summarize the relevance of blood gas values in and the effects on cellular function during hypothermia. HYPOTHERMIA, PCO 2 , AND pHPhysical laws determine that the solubility of a gas within a liquid decreases when lowering the temperature. During hypothermia, arterial PCO 2 decreases and pH increases compared with 37°C when measurements are made at the actual body temperature (Fig 1). In healthy subjects with a body temperature of 37°C, pH and PaCO 2 should approach 7.4 and 5.3 kPa (40 mm Hg), respectively. During hypothermia (33°C), pH will rise to 7.5 and PCO 2 will decrease to 4.5 kPa (34 mm Hg). PaCO 2 AND CEREBRAL BLOOD FLOWUnder normal conditions, term neonates autoregulate their cerebral blood flow in response to changes in systemic arterial pressure, but this mechanism can be impaired during neonatal distress. 7 In particular, changes in PaCO 2 have a well-recognized effect on cerebral blood flow. Hypocapnia induces cerebral vasoconstriction and may decrease cerebral tissue high-energy phosphates. 8,9 This effect has been extensively investigated in experiments in neonatal animals. [9][10][11] In preterm neonates, profound hypocapnia below values of 4 kPa (30 mm Hg) was related to periventricular leukomalacia. 12 There is little reason to assume that hypocapnia could not damage the brain in the sick term neonate. 13 Klinger et al 14 reported that in asphyxiated term neonates early hypocapnia was indepe...

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“…They found that the animals with pH‐stat management had better neurologic outcomes as demonstrated by performance scores and histopathological examination. Kurth and colleagues also examined the effects of pH‐stat vs alpha‐stat CPB strategy with DHCA in pigs. They examined the cortical oxygen saturation and found the pH‐stat group had higher cortical oxygen saturation and slower desaturations compared to the alpha‐stat group.…”

Section: Surgical and Cardiopulmonary Bypass Techniques And Their Impmentioning

confidence: 99%

Neurologic outcomes after heart surgery

Fang

Allen

Marino

et al. 2019

Pediatric Anesthesia

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Comparison of pH-state and Alpha-stat Cardiopulmonary Bypass on Cerebral Oxygenation and Blood Flow in Relation to Hypothermic Circulatory Arrest in Piglets

Cited by 74 publications

References 38 publications

Effect of deep hypothermic circulatory arrest followed by low-flow cardiopulmonary bypass on brain metabolism in newborn piglets: Comparison of pH-stat and α-stat management

Effect of deep hypothermic circulatory arrest followed by low-flow cardiopulmonary bypass on brain metabolism in newborn piglets: Comparison of pH-stat and α-stat management

Blood Gas Values During Hypothermia in Asphyxiated Term Neonates

Neurologic outcomes after heart surgery

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